The purpose of this study was to elucidate the effects of selenium-enriched probiotics on the liver of heat-27 stressed Wistar rats. Ten-week-old male rats were assigned to four groups: control (Con); high 28 temperature (HT); high temperature plus probiotics (HT+P: 10 11 CFU/mL Lactobacillus acidophilus and 29 10 9 CFU/mL Saccharomyces cerevisiae); or high temperature plus selenium-enriched probiotics 30 (HT+SeP: 0.3 mg/kg Se, 10 11 CFU/mL L. acidophilus and 10 9 CFU/mL S. cerevisiae). The HT, HT+P, 31 and HT+SeP groups were maintained at higher ambient temperature (40-42 °C), while the control group 32 were kept at room temperature (25 °C). After 42 days of thermal exposure, blood and liver tissues were 33 collected and analyzed for morphological and molecular markers of liver physiology. The body weight of 34 rats in the HT group decreased but liver weight and live index were increased. Histological examination 35 showed dilation of liver sinusoids and congestion of interstitial veins in HT group. Moreover, the 36 histomorphology of the liver in HT+P and HT+SeP groups was restored, and the serum AST, ALT, ALP, 37LDH and hepatic MDA level decreased significantly, but the serum total protein level and the liver SOD, 38 T-AOC, and GSH-PX activities were increased significantly relative to the HT group. In addition, the 39 mRNA level of Gpx1, SOD1, Nrf2, and Bcl-2 was significantly increased, while the expression level of 40 Bax, IL-6, TNF-α , COX-2, NF-κ B, α -SMA, TGF β 1, Collagen I, HSP70, and HSP90 was 41 significantly decreased in liver tissues after SeP supplementation. We concluded that SeP can protect 42 Wistar rats from oxidative stress, inflammation, apoptosis, and liver fibrosis induced by heat stress.
